When loaded with 10mm,my 10 round mags hold 10 and show 10 in the indicator holes. But when loaded with 10 9x25's it shows 9 and the mag will hold 11 before the #10 indicator hole shows a round. Yes I recounted 4 times. Same with my G20 mags, they hold 16 9x25 rounds, and it's effortless loading. I'm just not sure if it's over pushing the spring?
Any ideas?
Right now I've swapped it to 9x25, polished the barrel and the pin ends to match. It's loaded with 11+1 and I can snap the mag in with my thumb on the slide and my pinky on the magazine, no force at all. All my magazines are like this with 9x25. My spare mag is holding 16.
The bottle neck case relieves some tension at the front of the magazine, allowing additional rounds to fit.